This invention relates, inter alia, to novel compositions of matter useful, inter alia, as cocatalysts, to novel catalyst compositions made using such cocatalysts, to methods for preparing these catalysts, and to methods for polymerization utilizing the catalysts.
The use of soluble Ziegler-Natta type catalysts in the polymerization of olefins is well known in the prior art. In general, such systems include a Group 4 metal compound and a metal or metalloid alkyl cocatalyst, such as aluminum alkyl cocatalyst. More broadly, it may be said to include a mixture of a Group 1, 2 or 13 metal alkyl and a transition metal complex from Group 4-5 metals, particularly titanium, zirconium, or hafnium with aluminum alkyl cocatalysts.
First generation cocatalyst systems for homogeneous metallocene Ziegler-Natta olefin polymerization, alkylaluminum chlorides (AlR2Cl), exhibit low ethylene polymerization activity levels and no propylene polymerization activity. Second generation cocatalyst systems, utilizing methyl aluminoxane (MAO), raise activities by several orders of magnitude. In practice however, a large stoichiometric excess of MAO over catalyst ranging from several hundred to ten thousand must be employed to have good activities and stereoselectivities. Moreover, it has not been possible to isolate characterizable metallocene active species using MAO. The third generation of cocatalyst, B(C6F5)3, proves to be far more efficient while utilizing a 1:1 catalyst-cocatalyst ratio. Although active catalyst species generated with B(C6F5)3 are isolable and characterizable, the anion MeB(C6F5)3xe2x8ax96, formed after Mexe2x8ax96 abstraction from metallocene dimethyl complexes, is weakly coordinated to the electron-deficient metal center, thus resulting in a drop of certain catalytic activities. The recently developed B(C6F5)4xe2x8ax96 type of non-coordinating anion exhibits some of the highest reported catalytic activities, but such catalysts have proven difficult to obtain in the pure state due to poor thermal stability and poor crystallizability, which is crucial for long-lived catalysts and for understanding the role of true catalytic species in the catalysis for the future catalyst design. Synthetically, it also takes two more steps to prepare such an anion than for the neutral organo-Lewis acid.
In our prior applications referred to hereinabove, and in publications appearing in J. Am. Chem. Soc. 1996, 118, 12451-12452, Organometallics 1998, 17, 3996-4003, and J. Am. Chem. Soc. 1998, 120, 6287-6305 new, sterically encumbered fluoroaryl boranes such as tris(perfluorobiphenyl)borane (PBB), and the preparation and use of such compounds as a catalyst for ring opening polymerization of tetrahydrofuran (THF) and as a highly efficient cocatalyst for metallocene-mediated olefin polymerization are described. For example, PBB is a strong organo-Lewis acid which can be synthesized in much higher yield than B(C6F5)3. The anion generated with PBB is non-coordinating instead of being weakly coordinating as in the case of B(C6F5)3. Thus, the former exhibits higher catalytic activities and can activate previously unresponsive metallocenes. The catalytically active species generated with PBB are isolable, X-ray crystallographically characterizable instead of the unstable, oily residues often resulting in the case of B(C6F5)4xe2x8ax96. In addition, PBB exhibits even higher catalytic activities in most cases.
This invention provides, inter alia, technology described in the above-referred-to prior applications, and additionally, improvements in the technology described in the above-referred-to prior applications.
Accordingly, it is an object of the subject invention to provide, prepare and utilize new types of organo-Lewis acids that are useful in forming novel, highly-effective olefin polymerization catalysts.
A further object of the subject invention is to provide a catalyst which permits better control over molecular weight, molecular distribution, stereoselectivity, and/or comonomer incorporation.
Another object of the subject invention is to provide a Ziegler-Natta type catalyst system which reduces the use of excess cocatalyst and activates previously unresponsive metallocenes.
In accordance with one of its embodiments this invention provides novel organoboranes which may be represented by the formula
BRxe2x80x2nRxe2x80x33-nxe2x80x83xe2x80x83(I)
wherein Rxe2x80x2 is a fluoroaryl group having at least one additional substituent other than fluorine, wherein each Rxe2x80x3 is, independently, (i) a fluoroaryl group having at least one additional substituent other than fluorine, or (ii) a fluorinated aryl group devoid of additional substitution, and wherein n is 1 or 2. In these compounds both Rxe2x80x3 groups are preferably the same as each other and, preferably, are fluoroaryl groups having at least one additional substituent other than fluorine. Most preferably, n is 3, and each Rxe2x80x2 of formula (I) is the same as the other two. The substituent(s) other than fluorine present in the organoboranes of formula (I) can be (i) one or more substituents which increase the solubility of the compound in an organic solvent as compared to the corresponding compound in which each such substituent other than fluorine is replaced by a fluorine atom, (ii) one or more electron withdrawing substituents other than fluorine, or (iii) a combination of at least one substituent from (i) and at least one substituent from (ii).
A second embodiment provides organoboranes which may be referred to by the formula
BRxe2x80x2Rxe2x80x32xe2x80x83xe2x80x83(II)
where at least one of Rxe2x80x2 and Rxe2x80x3 is a fluorinated biphenyl or fluorinated polycyclic fused ring group such as naphthyl, anthracenyl or fluorenyl. Preferably two, and more preferably all three, of Rxe2x80x2 and Rxe2x80x3 are fluorinated biphenyl or fluorinated polycyclic fused ring groups such as naphthyl, anthracenyl or fluorenyl. Two of the biphenyl groups may be substituted with a phenyl group. That is, Rxe2x80x2 is a biphenyl group and each Rxe2x80x3 is a phenyl group. The biphenyl groups and the phenyl groups plus any polycyclic fused ring group or groups of the compounds of formula (II) should be highly fluorinated, preferably with only one or two hydrogen atoms on a group, and most preferably, as in PBB, with no hydrogen atoms and all fluorine substituents. Thus in one subgroup of these triorganoboranes Rxe2x80x2 of formula (II) is a fluorobiphenyl group having 0 to 2 hydrogen atoms and 7 to 9 fluorine atoms on the rings thereof, the sum of the foregoing integers being 9, and each Rxe2x80x3 of formula (II) is a phenyl group having 0 to 2 hydrogen atoms and 3 to 5 fluorine atoms on the ring, the sum of the foregoing integers being 5. In this subgroup most preferably Rxe2x80x2 is nonafluorobiphenyl and each Rxe2x80x3 group is a pentafluorophenyl group, i.e., the compound is nonafluorobiphenyl-bis(pentafluorophenyl)borane. In another subgroup of these triorganoboranes Rxe2x80x2 of formula (II) is a fluorobiphenyl group having 0 to 2 hydrogen atoms and 7 to 9 fluorine atoms on the rings thereof, the sum of the foregoing integers being 9, and each Rxe2x80x3 group of formula (II) is a fluorinated polycyclic fused ring group such as naphthyl, anthracenyl or fluorenyl. Preferably the polycyclic fused ring group is perfluorinated. However the fused rings may have one or two hydrogen atoms on the ring with the other available positions occupied by fluorine. A third subgroup of organoboranes of this second embodiment are tris(fluorobiphenyl)boranes wherein Rxe2x80x2 of formula (II) and each Rxe2x80x3 of formula (II) is a fluorobiphenyl group having 0 to 2 hydrogen atoms and 7 to 9 fluorine atoms on the rings thereof, the sum of the foregoing integers being 9, especially where such fluorobiphenyl groups are all the same as each other. The most preferred compound of this third sub-group is tris(perfluorobiphenyl)borane.
A third embodiment of this invention is comprised of organoboranes of the formula:
B(R1)n(R2)3-nxe2x80x83xe2x80x83(III)
wherein each R1 is, independently, a perfluorinated polycyclic fused ring group in which the ring system is totally aromatic (e.g., as in naphthyl or anthracenyl), or is partially aromatic and partially cycloaliphatic, (e.g., as in tetrahydronaphthyl, acenaphthyl, indenyl, or fluorenyl), wherein each R2 is a pentafluorophenyl group, and wherein n is 1 to 3. Such compounds include, for example:
tris(nonafluoroanthracenyl)borane,
bis(nonafluoroanthracenyl)(pentafluorophenyl)borane,
nonafluoroanthracenylbis(pentafluorophenyl)borane,
tris(undecafluorotetrahydronaphthyl)borane,
bis(undecafluorotetrahydronaphthyl)(pentafluorophenyl)borane,
undecafluorotetrahydronaphthylbis(pentafluorophenyl)borane,
tris(nonafluorofluorenyl)borane,
bis(nonafluorofluorenyl)(pentafluorophenyl)borane, and
nonafluorofluorenylbis(pentafluorophenyl)borane.
Compounds of this embodiment in which less than half of the fluorine atoms, and preferably up to about 3 fluorine atoms, are replaced by a corresponding number of substituents other than fluorine are included within the scope of the first embodiment described above.
A fourth embodiment of this invention provides a novel complex or ion pair formed from an organoborane of the first embodiment. In particular, the novel complex or ion pair of this fourth embodiment comprises a cation formed from a d-block or f-block metal compound by abstraction therefrom of a leaving group (e.g., a methyl group), and an anion formed by unification of the leaving group with an organoborane of the formula BRxe2x80x2nRxe2x80x33-n. In this formula, Rxe2x80x2 is a fluoroaryl group having at least one additional substituent other than fluorine, wherein each Rxe2x80x3 is, independently, (i) a fluoroaryl group having at least one additional substituent other than fluorine, or (ii) a fluorinated hydrocarbyl group devoid of additional substitution, and n is 1 or 2.
A fifth embodiment of this invention provides a novel complex or ion pair formed from an organoborane of the third embodiment. Thus in accordance with this fifth embodiment the complex or ion pair comprises a cation formed from a d-block or f-block metal compound by abstraction therefrom of a leaving group (e.g., a methyl group), and an anion formed by unification of the leaving group with an organoborane of the formula B(R1)n(R2)3-n. In this formula, each R1 is, independently, a perfluorinated polycyclic fused ring group in which the ring system is totally aromatic (e.g., as in naphthyl or anthracenyl), or is partially aromatic and partially cycloaliphatic, (e.g., as in tetrahydronaphthyl, acenaphthyl, indenyl, or fluorenyl), wherein each R2 is a pentafluorophenyl group, and wherein n is 1 to 3.
In a sixth embodiment of this invention, a novel catalytic complex or ion pair is produced by a process which comprises contacting a d-block or f-block metal compound having at least one leaving group (e.g., a methyl group) with an organoborane of the formula BRxe2x80x2nRxe2x80x33-n. In this formula, Rxe2x80x2 is a fluoroaryl group having at least one additional substituent other than fluorine, each Rxe2x80x3 is, independently, (i) a fluoroaryl group having at least one additional substituent other than fluorine, or (ii) a fluorinated hydrocarbyl group devoid of additional substitution, and n is 1 or 2. In this process, which typically is conducted in a suitable anhydrous liquid solvent and in a suitably inert atmosphere or environment, a leaving group is abstracted from the d-block or f-block metal compound and becomes unified with the organoborane to produce the catalytic complex.
A seventh embodiment is analogous to the process of the sixth embodiment except that the organoborane has the formula B(R1)n(R2)3-n wherein each R1 is, independently, a perfluorinated polycyclic fused ring group in which the ring system is totally aromatic (e.g., as in naphthyl or anthracenyl), or is partially aromatic and partially cycloaliphatic, (e.g., as in tetrahydronaphthyl, acenaphthyl, indenyl, or fluorenyl), wherein each R2 is a pentafluorophenyl group, and wherein n is 1 to 3.
An eighth embodiment of this invention is a process for polymerizing an olefinic monomer or copolymerizing two or more olefinic monomers, which process comprises contacting the monomer or monomers, preferably a single vinyl monomer or two or more copolymerizable vinyl monomers, with a polymerization catalyst complex which comprises a cation formed from a d-block or f-block metal compound by abstraction therefrom of a leaving group (e.g., a methyl group), and an anion formed by unification of the leaving group with an organoborane of the formula BRxe2x80x2nRxe2x80x33-n, wherein Rxe2x80x2 is a fluoroaryl group having at least one additional substituent other than fluorine, wherein each Rxe2x80x3 is, independently, (i) a fluoroaryl group having at least one additional substituent other than fluorine, or (ii) a fluorinated hydrocarbyl group devoid of additional substitution, and wherein n is 1 or 2.
A ninth embodiment is analogous to the polymerization process of the eighth embodiment except that the organoborane has the formula B(R1)n(R2)3-n wherein each R1 is, independently, a perfluorinated polycyclic fused ring group in which the ring system is totally aromatic (e.g., as in naphthyl or anthracenyl), or is partially aromatic and partially cycloaliphatic, (e.g., as in tetrahydronaphthyl, acenaphthyl, indenyl, or fluorenyl), wherein each R2 is a pentafluorophenyl group, and wherein n is 1 to 3.
These and other objects, embodiments, features and advantages of this invention will be apparent from the ensuing description, appended claims, and accompanying Drawings.